Short message service (SMS), which was first introduced by European wireless network operators in 1991, enables mobile subscribers to easily send and receive text messages via wireless handsets. Although specifications and industry standards related to SMS are constantly evolving and being modified, SMS messages have traditionally been used to convey readable text information, where the text can include any combination of characters that can be entered via a keypad or keyboard. Multimedia message service (MMS) extends the basic SMS concept to include a variety of message content types, including text, still images, video, and audio.
SMS delivery service provides a mechanism for transmitting messages to and from SMS capable terminals (e.g., wireless handsets, personal computers, etc.) via the signaling component of the wireless communication network. With particular regard to the sending and receiving of SMS messages by a wireless handset, a signaling network provides the transport facilities necessary to communicate short messages between a store-and-forward network element, known as a short message service center (SMSC), and a wireless handset. In contrast to earlier text message transmission services, such as alphanumeric paging, SMS technology is designed to provide guaranteed delivery of an SMS message to a destination. That is, if a temporary network failure, or the unavailability of a message recipient prohibits the immediate delivery of an SMS message, then the SMS message is stored in the network (i.e., at an SMSC) until the destination/intended message recipient becomes available. Another of the key and distinguishing characteristics of SMS service, with respect to previously available message communication services, is that an active mobile handset is able to send or receive a short message at any time, regardless of whether or not a voice or data call is in progress.
Other types of messaging services provided in a communications network may include those generically referred to as instant message (IM) messaging services. Instant messages are typically communicated between end users in real or near-real time without the use of intermediate store-and-forward processors. As such, IM services typically do not permit a message to be sent until the recipient is available.
FIG. 1 is a network diagram illustrating an SMS implementation in a global system for mobile communication (GSM) network. It will be appreciated that a functionally similar SMS architecture could also be employed in non-GSM networks, such as a session initiation protocol (SIP)-based network, or an IP multimedia subsystem (IMS) network. FIG. 1 includes a wireless communication network, generally indicated by reference numeral 100. Wireless network 100 includes a sending mobile station 102 that sends and receives SMS messages and a base station subsystem 104 that manages the network-to-air interface and reliably transmits SMS messages and from into the signaling portion of the network. In this particular example, the receiving end of the network includes a base station subsystem 106 and a receiving mobile station 108, both of which are functionally similar to devices 102 and 104 described above. Also included in wireless network 100 are mobile switching center/visitor location register (MSC/VLR) nodes 110 and 112, signal transfer points (STPs) 114 and 116, an SMSC 118, and a home location register (HLR) 120.
As described above, SMSC 118 is responsible for the relaying and store-and-forwarding of a short message between sending and receiving SMS terminals. HLR 120 is a database platform used for storage and management of mobile service subscriptions, mobile subscriber profiles, and locations. HLR databases store information about subscribers that belong to the same network as the HLR. In IP multimedia subsystem (IMS) networks, a network entity known as a home subscriber server (HSS) provides functionality and services similar to that of an HLR. That is, an HSS stores subscriber subscription, profile, and location information for subscribers of the same network as the HSS.
A database element, known as visitor location register (VLR) is used to temporarily store information about subscribers who are currently roaming in the area serviced by that VLR. The VLR may belong to the subscriber's home network or to a non-home network. Typically, VLR databases are co-located with MSC network elements, and as such a stand-alone VLR node is not shown in FIG. 1. The HLR and VLR store information needed to correctly route voice calls or data communications to the mobile subscriber. This information may include international mobile station identification (IMSI), mobile identification number (MIN), mobile directory number (MDN), and mobile station international ISDN number (MSISDN), as well as the IDs of the VLR and MSC with which the subscriber is currently associated.
With particular regard to short message service operations, HLR 120 may provide SMSC 118 with routing information for the receiving mobile station 108. In certain cases, HLR 120 may also inform SMSC 118, which has previously initiated unsuccessful short message delivery attempts to a specific mobile station, that the mobile station is now accessible.
It will be appreciated that MSC 110 is sometimes referred to as an SMS interworking MSC (SMS-IWMSC) because it is capable of receiving a short message from a wireless network and submitting it to the appropriate SMSC node. In a similar manner, MSC 112 is sometimes referred to as an SMS gateway MSC (SMS-GMSC) because it is capable of receiving a short message from an SMSC, interrogating an HLR for routing information, and subsequently delivering the short message to the visited or serving MSC of the recipient mobile station. In practice, SMS-GMSC/SMS-IWMSC nodes are typically integrated with the SMSC.
The signaling infrastructure of wireless network 100 is based on signaling system no. 7 (SS7), a telecommunications industry standard signaling protocol. A detailed discussion of SS7 signaling message types and their associated function can be found in Signaling System #7 by Travis Russell, McGraw-Hill Publishing 1998. Additionally, a detailed discussion of SS7 related signaling within a GSM network can be found in The GSM System for Mobile Communications by Michel Mouly and Marie-Bernadette Pautet, Cell & Sys 1992.
SMS service makes use of the SS7 mobile application part (MAP), which defines the methods and mechanisms for mobility management signaling communications in a wireless network. The American MAP standard is published by Telecommunication Industry Association and is referred to as IS-41 MAP, while the international standard is defined by the European Telecommunication Standards Institute and is referred to as GSM MAP. Depending upon the particular implementation, SMS service may also utilize the signaling connection control part (SCCP) and transaction capabilities application part (TCAP) components of the SS7 protocol. Within the context of SS7 signaling over Internet protocol (IP), an IP adaptation protocol such as the SCCP user adaptation (SUA) layer defined by the Internet Engineering Task Force (IETF) may also be utilized to facilitate SMS and MMS service. Other signaling protocols, such as session initiation protocol (SIP) may also be used to transport messaging service messages (e.g., SMS, MMS, IM) through a communications network.
FIG. 2 is an exemplary mobility management signaling message flow diagram associated with a typical location update operation triggered by roaming MS 108 shown in FIG. 1. When MS 108 roams into the coverage area served by MSC 112, MS 108 registers with MSC/VLR 112 (line 1), which triggers a location update transaction. The VLR component of MSC/VLR 112 generates an SS7 MAP UpdateLocation signaling message, which is routed to the mobile subscriber's HLR 120 (line 2). The UpdateLocation message includes information identifying the new serving MSC and VLR (MSC/VLR 112). The mobile subscriber's HLR 120 receives and processes the UpdateLocation message and, in response, sends the serving MSC/VLR information related to the roaming MS 108 (line 3). This mobile subscriber information is conveyed to MSC/VLR 112 in a MAP InsertSubscriberData signaling message. MSC/VLR 112 receives and processes the InsertSubscriberData message and responds to HLR 120 with an InsertSubscriberData_Ack message (line 4). The location updating transaction is concluded when HLR 120 sends an UpdateLocation_Ack message to MSC/VLR 124 (line 5). Once this mobility management procedure is completed, serving MSC/VLR 112 has obtained the information necessary to provide MS 108 with the network services which have been authorized, and HLR 120 has obtained the location information necessary to route calls or messaging service messages to the recipient MS.
FIG. 3 is an exemplary information flow diagram associated with the delivery of an SMS message to a MS 108 in a GSM network. Referring to FIG. 3, in line 1, a short message, such as a text message, is formulated by sending mobile station 102 and is subsequently transmitted to the mobile originated (MO) MSC/VLR 110, which is serving mobile station 108. In line 2, the short message content is communicated via a GSM ForwardShortMessage message to SMSC node 118. In response to receiving the ForwardShortMessage, SMSC 118 formulates an SMS send routing information (SRI) query message and transmits the SRI message to HLR 120 associated with the message recipient (line 3). HLR 120 responds to the SRI query and provides SMSC 118 with the network routing information required to deliver the short message to the mobile terminated (MT) MSC/VLR entity that is currently serving receiving MS 108. Upon receiving the network routing information, SMSC 118 transmits the short message to MT MSC/VLR node 112 (assuming the recipient MS is available), as indicated in line 4. Using the information obtained from the MT MSC/VLR database, paging and authentication operations are initiated, and MT MSC/VLR 112 transmits the SMS message to the receiving mobile subscriber, as indicated in line 5. Additional SMS delivery report and acknowledgment messages, not shown in this example, may also be generated within network 100 during an SMS message delivery transaction.
Based on the SMS delivery example described above, conventional methods for delivery of SMS messages require an HLR query for each SMS message to be delivered. One problem with requiring an HLR query for each SMS message is that the time for delivering each SMS message is increased. Another problem associated with requiring an HLR query for each SMS message is that signaling message traffic and HLR utilization are also increased. Accordingly, there exists a need for methods, systems, and computer program products for reducing or minimizing the volume of subscriber location register (e.g., HLR, HSS) query traffic associated with the delivery of messaging service messages, such as IM, SMS messages and MMS messages.